An integrated circuit (IC) may be designed to receive and provide logic signals at respective voltage levels that depend on the logic family of the IC or of a circuit coupled to the IC. Examples of logic families include Transistor-to-Transistor Logic (TTL) and Complimentary Metal-Oxide Semiconductor (CMOS) Logic. A TTL logic signal may be defined as having a low logic level (corresponding to a logic 0) when the signal has a voltage level that is less than or equal to 0.8 Volts (for example, a voltage level between 0.0 and 0.8 V), and may be defined as having a high logic level (corresponding to a logic 1) when the signal has a voltage level greater than or equal to 2.2 V (for example, a voltage level between 2.2 V and 3.0 V). In contrast, a CMOS logic signal may be defined as having a low logic level (logic 0) when the signal has a voltage level that is less than VCC/2 (for example, less than 2.5 V when VCC=5.0 V), and may be defined as having a high logic level when the signal has a voltage level greater than VCC/2 (for example, greater than 2.5 V when VCC=5.0 V).
Although an IC may be designed to receive and transmit logic signals according to the specifications of one logic family via its external input/output (I/O) pins, the IC may generate internal logic signals according to the specifications of another family. For example, an IC may be capable of receiving and transmitting TTL logic signals externally, but may generate CMOS logic signals internally. Therefore, such an IC translates a received input TTL logic signal into an internal CMOS logic signal, and translates an internal CMOS logic signal into a transmitted external TTL logic signal. Consequently, each I/O pin on such an IC may be coupled to an I/O buffer that translates TTL logic levels to CMOS logic levels and vice-versa.
A conventional I/O buffer, however, may have various problems. For example, the bandwidth of the buffer may be limited, or the buffer may draw a significant quiescent current (sometimes called leakage current, static high current, or ICCT), which may result in significant quiescent power consumption that may reduce battery life in mobile devices.